Discocactus diersianus
Discocactus diersianus is a species of Discocactus found in Brazil.
Description
Discocactus diersianus is a small, solitary cactus, sometimes form clumps if damaged by fire. The cactus has an olive-green to dark green epidermis and a discoid to flattened globose stem, measuring tall and in diameter, supported by branched roots. Its stems feature 13 to 18 distinct, vertically or slightly spirally arranged ribs, each with a V-shaped groove below the areoles and divided into rounded tubercles. Oval, sunken areoles, long and wide, are situated on these tubercles, with 4 to 6 per rib, and are the origin of the spines. These spines, typically gray to brownish-gray or blackish-gray with dark brown to black tips, are strongly curved or hooked and rounded or quadrangular in cross-section. They consist of a single, sometimes absent, central spine up to long, accompanied by 4 to 10 radial spines ranging from in length.Adult plants develop a distinctive woolly cephalium at their apex, reaching in height and up to in diameter. This structure, composed of white wool and accented by brown to reddish bristles up to long at its margin, serves to protect the plant's sensitive tip from cold nights and intense UV radiation, and is also thought to attract pollinators due to its conspicuous nature even before flowering. The white, fragrant flowers emerge from the cephalium's edge, opening at night and pollinated by moths. They are tubular to narrowly funnel-shaped, measuring in length and in diameter, with white to greenish buds. The pericarpel is naked at the base, with few scales in the upper axils, while the thin, greenish-white floral tube has light green to white scales. The inner perianth segments are about long and white, and the outer segments are approximately long, white with a red tip. Inside, the stamens have filaments long and cream-colored anthers long, while the style is long and bears a 4 to 6 lobed stigma. The ovules, arranged in clusters of 2 to 3, have often branched funicles covered with fine hairs. The fruits are slender and club-shaped, white to cream-colored with a greenish to brownish tint near the apex, measuring about long and wide. They split longitudinally at maturity, retaining persistent floral remnants, and contain 70 to 80 shiny, oval black seeds, each long with a testa featuring more or less elongated tubercles.